This message is almost a week old, but I want to reply anyway because I had to take two weeks off upper body a month ago and I was freaking out too, I know how you feel. Anyway, I really didn't notice a difference, and in fact I feel a little stronger now. I took the two weeks off (I had biceps tendinitis) then went a little lighter for a week, then back to what I was lifting before. So don't stress out, enjoy the rest, and you'll be fine!